Injection molding is a technology commonly used for high-volume manufacturing of parts constructed of thermoplastic materials. During repetitive injection molding processes, a thermoplastic resin, typically in the form of small pellets or beads, is introduced into an injection molding machine which melts the pellets under heat and pressure. The molten material is then forcefully injected into a mold cavity having a particular desired cavity shape. The injected plastic is held under pressure in the mold cavity and subsequently is cooled and removed as a solidified part having a shape closely resembling the cavity shape of the mold. A single mold may have any number of individual cavities.
Injection molding machines operate within manufacturer-provided constraints to ensure safety and operability of the machine. These machines are typically constrained by maximum load values which act to limit any number of operating parameters of the injection molding machine to ensure safe and effective operability and avoid damage to components of the injection molding machine. In the event that the manufacturer's safety margin level, as contrasted to the machine's actual maximum load value for a given set of operating and environmental conditions, is exceeded, the machine may overheat, trip to a failsafe setting, and/or trigger an alarm condition. The maximum load value may be represented graphically, and it may be dependent on any number of variables, such as, for example, equipment operating speeds, pressures, the type and viscosity of material(s) being molded, as well as environmental conditions. Because of the presence of maximum load values, the machine may be permanently configured to operate at or below particular variables regardless of whether the machine is operating above the maximum allowable load prescribed by the manufacturer.
Generally speaking, injection molding machines allow an operator to modify and/or manipulate the operating parameters thereof. As a merely illustrative, non-limiting example, if an environmental factor such as a plant ambient temperature causes the injection molding machine to work harder (i.e., consume more energy) to generate parts, the machine's operating load value over a given period of time will increase. This increase in the operational load value may eventually cause the machine to approach or exceed the maximum load value which, may result in temporary or permanent machine failure. Prior to exceeding, or even reaching, this maximum load value, the machine may be pre-programmed to generate an alarm which prompts a machine operator to adjust operating variables as required to lower the operating load on the machine, or may trigger the machine to reduce or even cease molding operations altogether, i.e. trip to a safety mode.
By relying on the machine operator to adjust operating parameters of the machine, adjustments may not be made as frequently as optimal. For example, if the injection molding machine is operating overnight with a limited number of operators on duty, there may be an extended period in which parameters are not altered. Further, an operator may not realize when the characteristics causing the machine's load value to change have subsided, and thus may keep the machine running in an operational mode which fails to fully utilize the injection molding machine's efficiency. Further still, different operators may employ different approaches to adjusting the machine, and some operators may be less inclined to adjust settings as frequently as others.
Machines may be configured to provide a safety margin below a maximum machine load based on a “worst-case scenario,” that is, when any number of parameters are present that would dramatically impact operability of the machine. The restrictions applied to the machines (e.g., safety factors) may restrict the machine from operating within a certain percentage of the maximum machine load. As a result, in operating conditions that resemble the worst-case scenario (such as environments with high ambient temperatures and/or pressures, materials having abnormally high viscosities, thus impacting flow speeds and cooling times, and the like), the machine is limited to performing at a level that is less than its peak performance. Similarly, even in the presence of operating conditions which are considered favorable or preferred, due to the fact that the manufacturer's pre-programmed safety factors are set with worst-case scenarios in mind, and are often not easily overridden, it is often the case that conventional injection molding systems do not approach peak efficiency outputs, even in the most ideal of operating conditions.
Frequently, injection molding machines are configured by the manufacturer to fix the range of adjustability of certain operator-adjustable parameters in an injection molding operation, or even prevent any operator adjustment of certain parameters, based on operator adjustment of other parameters. For instance, if an operator sets up an injection molding machine to implement molding operating program that contemplates injecting a viscous molten thermoplastic material at particularly aggressive velocity in a given portion of each injection molding cycle, the machine may be pre-programmed to only permit the injection molding machine's electric, hydraulic, servo-hydraulic, or servo-driven screw to accelerate at a conservative rate of acceleration, and/or to operate at a conservative pressure, based on the manufacturer's built-in safety margin below the machine's actual load capacity.